1. Autotrophic Nutrition

2. All Organisms Need Energy
All organisms require energy to live. There are two main ways to obtain this necessary energy:
Cells use energy trapped in chemical bonds. When these bonds are broken, energy is released for cellular activities.
When cells use several linked chemical pathways to create the energy needed, this is called a biochemical pathway.
AUTOTROPHS
HETEROTROPHS

3. Storage and Release of Chemical Energy
Energy is stored (in a “high energy” bond) when a phosphate group is added to ADP.
Energy is released from ATP when a phosphate group is removed (the “high energy” bond is broken)
Note: This same system works between NADPH and NADP+

4. Visible Light Light travels as waves of energy
Reflection, Transmission, Absorption

5. Nutrition
Nutrition: an organism’s ability to obtain and process materials needed for energy, growth, repair and regulation.
Two type of nutrition:
Heterotrophic – “eat” their food
Autotrophic - make their own food

6. Autotrophic Nutrition
Autotrophs produce their own food (sugar) from inorganic compounds.
Autotrophs produce sugar through the process of PHOTOSYNTHESIS

7. What is Photosynthesis?
Photosynthesis: plants use energy from the sunlight to convert carbon dioxide (CO2) and water into oxygen (O2) and sugar.
The equation for photosynthesis:
6 CO2 + 6 H2O C6H12O6 + 6 O2
light
Temperature and Light Intensity can both affect the rate of photosynthesis, but it will either decrease or level off at some point.

8. 5 things needed for photosynthesis
Water
Sunlight
Carbon Dioxide
Chlorophyll (a light capturing pigment)
Enzymes

9. Where does photosynthesis occur?
In the chloroplasts!
Remember
the elodea?

10. Structure of the Chloroplast

11. Structure of Chloroplast
The chloroplast is surrounded by a double membrane.
Thylakoid = membrane that contains CHLOROPHYLL
Grana = stack of thylakoids
Stroma = fluid portion of the chloroplast

12. Pigments in plants
(Chlorophyll) Pigments: proteins that trap light energy from the sun, photosynthesis depends on this absorption of light to begin.
Why do pigments appear as different colors?
EXAMPLES:
Chlorophyll : Appears green
A: Traps Red Light
B: Traps Blue Light
Accessory Pigments: Trap green/yellow
Carotene: Appears orange
Xanthophyll: Appears yellow
The least important color for photosynthesis?
GREEN!!

13. Photosynthesis Overview

14. Light-Dependent Reactions
Photolysis – energy from the Sun is used to split H2O.
O2 is released
ATP and NADPH (energy-rich molecules) are made

15. The Light-Dependent Reactions
Location: occurs in the thylakoid membranes
Function of First Stage:
Harvested light energy is converted from sunlight to electrical energy (ETC)
Uses energy from the sun to produce ATP and NADPH needed for next reaction
Important events you should know:
Chlorophyll is energized
Water is split
ATP and NADPH are formed
Hydrogen is trapped

16. The Light-Dependent Reactions
☼ (photons/light energy) ↓
Pigments in photosystem II and then photosystem I absorb energy
Electron Transport Chain
↓ ↓
Energy splits H ADP  ATP*
↓ ↓
O H trapped by NADP+
(forms NADPH *)
Energy used to form ATP from ADP
Both products here are used in the dark (light-independent) reaction

17. Electron Transport Chain
Process starts in a photosystem located on a thylakoid.
Absorption: Photosystem II absorbs energy from photons
Passage: electrons are passed to Photosystem I.
Transfer: electrons are transferred along the chain generating “electricity”.
Splitting: Electricity drives the splitting of water to form H+ and free oxygen.
Formation: Electrons provide energy for NADP+ to gain a H+ and form NADPH, also ATP is formed
ATP and NADPH are then used in the Dark Reaction/Calvin Cycle
Light Reaction Video

19. Light Dependent Reaction Video

20. Calvin Cycle (Light-Independent)

21. Calvin Cycle
Calvin Cycle (Dark/Light-Independent Reactions):
Location: takes place in the stroma Function: Uses energy from ATP and NADPH to produce high energy carbohydrates (sugars)
Does not require light to occur (can actually occur in light or dark)
Reactions form organic compounds using energy stored from Light-dependent reactions in bonds of NADPH and ATP
Named after American scientist, Melvin Calvin, who discovered this in the early 1950’s

23. The Calvin Cycle/Dark Reaction
These reactions can occur with or without Light!!
This begins and ends with RuBP = a 5-carbon sugar found in chloroplasts
CO2 + RuBP + ATP* (from Light Reaction) ↓
2(PGA) + 2H* (from Light Reaction)
 
2(PGAL) H20 (released as a waste product)
 
RuBP (80%) Glucose (20%)
Calvin Cycle Animation
CO2 given off

24. Calvin Cycle Diffusion: Carbon dioxide diffuses into the stroma
Carbon Fixation: CO2 binds with 5-carbon molecule called RuBP. This forms an unstable 6-carbon molecule.
Splitting: This six carbon unstable molecule splits immediately into two molecules called PGA.
Conversion: PGA is changed into PGAL when:
A. PGA receives phosphate group from an ATP molecule from the light reaction
B. PGA accepts Hydrogen Ions from NADPH also from the light reaction
In summary, the Calvin Cycle fixes carbon dioxide and regenerates RuBP, produces PGA, then PGAL which may be converted to glucose.

25. The Leaf
The CO2 required by the plant enters through stoma (tiny openings under the leaf).

26. Guard Cells Guard Cells: open and close the stoma on a leaf
Regulates water loss and temperature
Open – after rain or during cool days
Closed – drought or hot days (prevent water loss), but may open to allow for evaporation (lower temperatures)

27. Guard
Cell
Stoma

29. Plants convert light energy into chemical energy through the process of PHOTOSYNTHESIS
This is AUTOTROPHIC NUTRITION

30. Guard
Cell
Stoma